Quorum Sensing

Category: Microbiology & Biotechnology | GS Paper III

SEO Title: Quorum Sensing in Bacteria: Mechanism, Biofilm Formation, Virulence and Antibiotic Resistance

UPSC Notes

Quorum sensing is a form of cell-to-cell communication through which bacteria detect population density and coordinate gene expression.

  • Mechanism: Bacteria release chemical signalling molecules called autoinducers.

  • Population sensing: As the bacterial population grows, signalling molecules accumulate in the surrounding environment.

  • Gene regulation: When a signalling threshold is reached, bacteria alter the expression of selected genes.

  • Biofilm formation: Quorum sensing can regulate biofilm development, maturation and dispersal in certain bacteria.

  • Virulence: Some pathogens use quorum sensing to coordinate toxin production, secretion systems or other disease-related traits.

  • Bioluminescence: A well-known example occurs in luminous marine bacteria such as Aliivibrio fischeri.

  • Antimicrobial resistance: Biofilms and coordinated bacterial behaviour can contribute to antimicrobial tolerance; quorum sensing is one factor among several and is not itself synonymous with antibiotic resistance.

  • Research applications: Quorum-quenching approaches aim to disrupt signalling and may help develop alternative strategies for controlling certain infections.

Key Pointers

  • Quorum sensing is chemical communication among microbial cells.

  • Autoinducers are the signalling molecules.

  • It can regulate biofilm formation and virulence.

  • It is distinct from horizontal gene transfer, although both are relevant to microbial adaptation.